UV-curable waterborne polyurethane coatings: A state-of-the-art and recent advances review

Abstract

Waterborne polyurethane coatings prepared by UV-induced photoreactions (UV-WPU) are becoming very attractive due to the increasingly stringent environmental demands. They were developed to replace solventbased polyurethanes in the coatings of wood, paper, plastics, metal, and glass, mainly because of their good physicochemical, rheological, and optical properties. Several UV-WPU formulations have been tested over the years, making their research substantial. However, no valuable review of this literature, focusing on the significant influencing factors in UV-WPU's manufacture, is available to date. This work aims to answer specific questions about the state of these materials' art, such as: "which monomers have been used most in UV-WPU synthesis?", "what type of photo-initiator has promoted the most efficient curing of the material?", "what additives or particles have been tested for composite UV-WPUs?", "which applications have UV-WPUs been directed to?", "what adaptations and technologies have already been tested to overcome the challenges of the process?", among others. As a result of a systematized bibliographic search in four databases, considering the period from January 2000 to July 2020, a total of one hundred and thirty-eight distinct and relevant articles on UV-WPUs were found. From this study, we hope to present a scientific source on the current state-of-the-art of UV-WPU synthesis, providing new combinations of raw materials and intelligent solutions, thus making material and industrial engineers able to mitigate the inconveniences of the process.

Efficiency of castor oil–based polyurethane foams for oil sorption S10 and S500: Influence of porous size and statistical analysis

“…12,22,23 The triglycerides’ hydrophobic essence presented on castor oil proportionate excellent chemical and mechanical properties, such as high tensile strength, elongation, and thermal stability. 5,22,24,25 The main properties of PU foams are attributed to the density and morphological structure, which are influenced by the concentrations of polyol and isocyanate, resulting in different foam structures (flexible, semi-flexible, or rigid). 10,22,23,26–29 About 60–70% of the polyurethane properties are defined by the reagents employed.…”

Coating Process Optimization and Self-Healing Performance Evaluation of Shellac Microcapsules Coated with Melamine/Rice Husk Powder

“…Compared with traditional organic coatings, waterborne coatings on wood surfaces have the advantages of safety, innocuity, wear resistance and good chemical resistance [1][2][3][4], but it is necessary to improve the physical and mechanical properties [5][6][7]. Recent studies have shown that it has a broad research prospect on regulating the characteristics of coatings on a wood surface and inhibiting their defects by adding microcapsules [8][9][10].…”

Bio-Based Hydrogel and Aerogel Composites Prepared by Combining Cellulose Solutions and Waterborne Polyurethane

“…The obtained WPU resin is nontoxic, nonflammable, nonpolluting, and is a good environmentally friendly material. The dried resin film has good mechanical properties, flexibility, gloss, and weather resistance [ 31 ].…”